It is currently working for Google, Yahoo and Bing search engines. You can add desired rules (with regular expressions) in the options page. When a rule is matched with a redirect URL, it is blocked (or redirected) and therefore the host server won't be able to track you.
You can add any regular expressions that you would like in the options page. But please note that you need to add rules comma separated. Before adding the rules please make sure they are working correctly otherwise it might break the add-on. Bade icon text shows you the number of blocked URLs.
In order to report bugs, please fill the bug report form in the add-on's homepage.
